If i understand your question corrctly, you want to populate a checkbox list with elements from a comma sperated list?
That's easy if you use the addrange method:
Page_Load(object sender, EventArgs e){
if(!IsPostback)
LoadcheckboxList();
}
private void LoadCheckboxList(){
var csvTypeLikeColumn = "Certificate,Passport,..";
var cbl = new CheckBoxList();
cbl.Items.AddRange(csv.Split(",".ToCharArray()));
}